Self-compensating centrifugal governor



May 18, 196 E. ELLNER ETAL SELF-COMPENSATING CENTRIFUGAL GOVERNOR 2 Sheets-Sheet 1 Filed Aug. 3. 1961 FIG. 1

ATTORNEYS y 13, 1955 E. ELLNER ETAL 3,184,562

SELF-COMPENSATING CENTRIFUGAL GOVERNOR Filed Aug. 3, 1961 2 Sheets-Sheet 2 FIG. 6

INVENTORS EDWIN ELLNER BY PHILIP R. BURROWS ATTORNE S United States Patent Office 3,184,562 Patented May 18, 1965 3,184,562 SELF-COMPENSATING CENTRIFUGAL I GOVERNOR Edwin Ellner, Oxford, and Philip R. Burrows, Middlebury, Conn., assignors to Consolidated Electronics Industries Corp., Waterbury, Comm, a corporation of Delaware Filed Aug. 3, 1961, Ser. No. 129,tl18 8 Claims. (Cl. Mil-80) The present invention relates to governing devices for electric motors and the like, and is directed more specifically to a novel and improved centrifugal governor which is highly responsive to the centrifugal forces resulting from the rotational movement of a motor or other element but is substantially completely unresponsive to miscellaneous external forces resulting from acceleration and shock, for example. The device of the invention is particularly useful for air and space applications, for example, where the parts of a mechanism may be subjected to significant external acceleration forces.

In accordance with the present invention, a novel and improved centrifugal governor is provided which includes contact elements actuated by masses which are mounted for movement in response to centrifugal forces arising from the rotation of a motor shaft or other element on which the governor device is mounted. The mounting of the contact members and the actuating masses is such, according to the invention, that forces other than purely centrifugal forces arising from rotation are ineffective to urge the contact members in either a contact-opening or contact-closing direction. More specifically, the mounting of the Contact members and their actuating Weights is such that external forces applied in one direction have no effect'whatever, and external forces applied in a direction at right angles have an effect on one contact member which is effectively nullified by a compensating action on another contact member.

Although the centrifugal governor device of the invention may take a variety of specific forms, the generic form of the invention involves the use of two contact arms mounted at one end for swinging or pivoting movement and carrying electrical contact elements at their other ends. Each contact arm mounts a predetermined weight or mass, and the separate arm assemblies are mounted symmetrically with respect to the axis of rotation of the motor or other rotary element whose speed is to be controlled. The center of gravity of each contact arm assembly is such, in relation to its effective pivot point or mounting point, that the axis extending between such points and the center of gravity is at right angles to the direction of movement of the contacts in opening and closing. Accordingly, forces directed along such axes will have no tendency whatever to either open or close the contacts. At the same time, external forces directed along the axis of opening and closing movements of the contacts, while tending to move one contact in a closing direction, for example, will simultaneously tend to move the other contact in the opening direction, so that such forces are without net effect. As will be readily understood, all external forces acting in a transverse direction, will consist of components in the two right angularly related directions previously mentioned, such that the improved governor device is substantially completely immune to the effect of external forces.

The improved centrifugal governor device of the invention also includes improved features of construction facilitating manufacture of the device in miniature sizes and at low cost. In addition, the improved device facilitates the incorporation of spring return means of long effective length. Advantageously, the governing device of the invention is employed in reversely orientated pairs, for improved dynamic balance of the rotating system and for improved accuracy of control.

For a better understanding of the invention, reference should be made to the following detailed description and to the accompanying drawing in which:

PEG. 1 is a longitudinal elevational view, partly in section, of an electric motor incorporating the new centrifugal governor of the invention;

FIG. 2 is an enlarged cross sectional view taken generally along line 22 of FIG. 1;

PEG. 3 is a plan view similar to FIG. 2, of a first moditied form of the new governing device;

FIG. 4 is a side elevation of the device of FIG. 3;

FIG. 5 is a plan view of a second modified form of the governing device;

FIG. 6 is an elevational view of the device of FIG. 5; and

FIG. 7 is a simplified, schematic representation of an advantageous motor governing circuit incorporating the new governor.

Referring now to the drawing and initially to FIGS. 1 and 2 thereof, the reference numeral 10 designates generally the housing of a motor assembly, which includes a stator ill and rotor 12. The rotor includes a shaft 13 which typically is journaled in a bearing 14 mounted in an end plate 15 of the motor housing. The motor may be approximately three-quarters of an inch in diameter, although the device of the present invention is not limited by the dimenisons of its parts.

Between the end of the rotor 12 and the shaft-supporting bearing 14 there is advantageously secured a circular mounting plate 16, the plate being fixed to the shaft for rotation therewith. In the device of FIG. 1, the Plate 16 mounts a pair of similar but revcrsely orientated centrifugal governor assemblies generally designated by the reference numerals l7 and 18, it being understood that, except for reverse orientation, the respective governor assemblies l7, 1% are substantially identical in construction and only one of the assemblies will be described herein, in detail.

Referring now more particularly to FIG. 2, the mount ing plate 16 of the new governor device has fixed thereto a pair of stud posts 19, 29, which are disposed symmetrically with respect to an imaginary axis extending vertically in a drawing and passing through the rotor shaft 13. The stud posts 19, 20 are slotted to receive and anchor the end extremities of two contact arm members 21, ZZand, advantageously, the end portions of the contact arms are wound in spiral fashion to provide spiral spring sections 23, 24 having several effective convolutions. As indicated in FIG. 2, the contact arms 21, 22 are disposed symmetrically with respect to the imaginary vertical axis, and the orientation of the spring portions 23, 24 thereof is such as to urge the contact arms to pivot inward toward the vertical axis.

The contact arms 21, 22 pass on opposite sides of the rotor shaft 13 and, in the general region of the rotor shaft, the arms are deformed away from the shaft to afford ample clearance. This is indicated at 25, 26 in FIG. 2. The upper end portions of the contact arms 21, 22 are deformed inwardly, and the upper end extremities 27, 28 mount electrical contact elements 2d, 3d, respectively. The arrangement is such that, under normal, static conditions, the contact elements 29, 39 are engaged at the imaginary vertical axis under the urging of the spiral spring portions 23, 24.

Each of the contact arms 21, 22 mounts a predetermined weight or mass 31, 32, which, in conjunction with the effective mass of the contact arms and their contact elements, bears a predetermined relation to the effective sneer-see force of the spring portions 23, The masses 3 1, 32 are disposed symmetrically with respect to the imgainary vertical axis, and the arrangement of the elements is such, that upon rotation of the mountin plate with the rotor shaft, the effective masses of the contact arm assemblies are acted upon by centrifugal forces proportional to the speed of rotation. In accordance with known practice, the effective masses of the contact arm assemblies are such, in relation to the effective portions of spring portions 23, 24, that the contacts 29, 31 will separate at a predetermined rotational speed to break the power circuit to the motor. Alternatively, the contact arm assemblies may be critically designed to vibrate at a high rate of speed in opening and closing directions, with the effective centrifugal forces being utilized to vary the relative periods of contact closure and separation within the normal vibrating cycle.

In accordance with a specific aspect of the invention, the symmetrically arranged contact arm assemblies have their respective centers of gravity so located that an imaginary axis extending through the center of gravity of a Contact arm assembly and through the effective pivot point thereof lies at right angles to the direction of opening and closing movement of contact elements 29, 30. Thus, with reference to FIG. 2, for example, the opening and closing movements of the contact elements 29, 30 will take place substantially along a horizontal axis. Accordingly, the axis extending between the centers of gravity of the contact arm assemblies and their effective pivot points will extend in a vertical direction.

As will be understood, externally applied acceleration and/ or shock forces which are oriented vertically with respect to the illustration of FIG. 2 will exert no rotational moment whatever upon the contact arm assemblies and therefore will have no tendency to open or close the contact elements 29, 30. External forces applied horizontally with respect to the view of FIG. 2, will, of course, exert a rotational moment upon the respective contact arm assemblies. However, the effect of such forces on the separate contact arm assemblies is mutually compensating, so that there is no net effect tending to open or close the contacts 29, 30. Thus, assuming an acceleration force is applied in a horizontal direction from the left, for example, the contact arm assembly including the arm 21 and mass 31 will tend to move to the right, or in a contact closing direction. At the same time, the assembly, including the contact arm 2-2 and the mass 32 will also move to the right, or in a contact opening direction. lhe net elfect at the contact surfaces is substantially nil, and opening and closing of the contacts remains substantially fully responsive to the centrifugal forces arising from rotation of mounting plate 16.

As will be understood, forces applied externally in any direction whatever to the motor and governor assembly of FIG. 1 can be broken down for analysis into three vector components, one directed axially along the rotor shaft 13, one directed vertically with respect to PEG. 2 and one directed horizontally with respect to P16. 2. None of these force components has an effective opening or closing influence on the contact elements 29, 351, by reason of the unique arrangement of the elements of the new governor, such that extremely accurate and responsive rotational speed regulation may be realized notwithstanding substantial external regulation or shock forces such as might be expected in connection with units installed in high speed military aircraft or in rockets, for example.

In the form of the invention illustrated in FIGS. 1 and 2, a pair of governor mechanisms 17', 18 is mounted on the plate 16, with the individual mechanisms being oppositely disposed for improved dynamic balance and especially reliable control. Advantageousiy, the separate devices are connected in series with two opposed windings of the rotor substantially as indicated at A and B in FIG. 7. In the specific circuit therein illustrated, incorporating an odd number of series connected windings (in, seven) opening of the governor contacts substan- 3. tially reduces the average current flow by opening the armature circuit in most positions of the rotor. Where an even number of windings is employed, opening of the governor contacts completely cuts off the armature current. in either case, the rotor is slowed for governing control by opening of the governor contacts.

The arrangement of FIG. 7 is especially advantageous in connection with small motors, since it makes possible the elimination of slip rings otherwise normally required to supply current to the governor switches. The switches are connected directly in series with two opposed armature coils and current is supplied to the coils in a conventional manner, through a commutator C having a segment for each winding connected to a point between two adjacent windings.

Advantageously, the stud posts 19, 20 extend completely through the mounting plate 16 to facilitate making electrical connection from the opposite side of the plate where desirable or expedient. In addition, where dual governor assemblies are utilized, as in the assembly of FEGS. 1 and 2, the projecting end portions of the stud posts (see 2012 in FIG. 1) serve as banking posts, to limit movements of the contact arms. In FIG. 2, for example, posts 33, 34, mounting the respective contact arms of the governor assembly 18, extend through the mounting plate on opposite sides of the contact arms 21, 22.

Advantageously, the posts 19, 2d and 33, 34 are secured to the plate 15 by glass-to-rnetal seal, affording the necessary insulation While at the same time insuring substantial dimensional stability and rigidity, particularly over the military temperature range of 55 C. to C. (and higher), where most plastic materials, for example are not stable. A typical glass-tornetal mounting is illustrated at 35, 36 in FIG. 2.

In a modified form of the invention illustrated in FIGS. 3 and 4 only a single governor mechanism is indicated, although it will be understood that the mechanisms may be used in pairs, as indicated in FIGS. 1 and 2, where appropriate. In principle, the mod fied form of the invention illustrated in F163. 3 and 4, is substantially the same as that of FIGS. 1 and 2. However, its specific features of construction are different in pertinent respects.

Referring again to the drawing, and now particularly to FIGS. 3 and 4, the reference numeral designates a mounting plate which is fixed to a rotor shaft 111 for rotation therewith. A pair of stud posts 1 12 and 11? project outward from the face of plate 111 and mount for pivotal movement bushings 114, 115 of respective contact arms 116, 117.

In the illustration of PIG. 3, the contact arms 116, .117 are symmetrically disposed with respect to an imaginary vertical axis through the shaft 111, and the arms pass on opposite sides of the shaft in relatively wide separation to afford ample clearance. The free or lower ends of the contact arms are deformed inward, as 118, 119 and mount respective contact elements 12% 121. Each of the contact arms also mounts a predetermined weight or mass 122, 123, so arranged that the respective centers of gravity of the contact arm assemblies lie along axes extending through the centers of rotation of the contact arms and disposed at right angles to the direction of opening and closing movements of the contacts 12%, 121.

In the modified governor device, the mounting plate 11% is provided with radial key 124 which guides an adjustable slide element 125. A screw 126 is engaged in the key 124 and is received in elongated slot 127 in the slide, the arrangement being such that the slide is adjustable radially but may be secured in any predetermined position within its range of movement by tightening the screw 126.

A pair of extensible coil springs 12%, 129 connect the res ective contact arm assemblies 116, 117 to the adjustable slide 125' and act to urge the contact arms in a closing direction. Advantageously, the springs 128, 129 .are disposed at a substantial angle with respect to the opening :and closing directions of the contact arm assemblies, to provide for substantially increased effective spring length and greater precision of adjustment. In addition, the long effective spring length enables a high degree of accuracy to be maintained over an extended operating period, notwithstanding considerable contact wear, since the contact wear does not have an appreciable affect upon the spring force, as is ordinarily the case with conventional mechanisms.

In substance, the operation of the device of FIGS. 3 and 4 is the same as that of the device of FIGS. 1 and 2, that is, the arrangement of the contact arm assemblies is such that the various right angula-rly related components of externally applied force have no net effect upon opening or closing of the contact elements 120, 121. This is assured by disposing the center of gravity and pivot axis of each contact arm .assembly along an axis at right angles to the direction of opening and closing movements of the contact elements and by providing for contact opening and closing with two symmetrically arranged contact assemblies, whereby externally applied force components acting in the direction of contact opening and closing are efiectively nullified by the mutually compensating actions of the respective contact arm assemblies.

In the further modified form of the invention shown in FIGS. 5 and 6, a mounting plate 210 is secured to a shaft 211 for rotation therewith and has formed on one edge a mounting block 212. A pair of contact arms 213, 214 are secured by screws 215, 216 to the mounting block and extend in generally parallel relation on opposite sides of the shaft 211. The free ends of the contact arms are deformed inward and mount contact elements 217, 218, which normally are held in contacting engagement by reason of the inherent resilience of the contact arms, which are maintained under a predetermined spring tension through appropriate mounting on the block 212. As in the previously described embodiments, the contact arm assemblies are symmetrical with respect to a diametric axis passing through the shaft 211 (vertically in FIG. 5).

Each contact arm 2'13, 214 mounts a predetermined mass 219, 220 calculated to overcome the spring bias of the contact arms by outwardly acting centrifugal force upon attainment of a predetermined rotational speed.

The modified device of FIGS. 5 and 6 is similar in significant respects to the device of FIGS. 1 and 2, ex cept with regard to the mounting of the contact arms. Thus, whereas the device of FIGS. 1 and 2 incorporates spiral spring means of substantial effective length for mounting the contact arm assembly, the contact arms 213, 214 of the device of FIGS. 5 and 6 are mounted directly on block 212 and are urged in a closing direction by inherent resilience providing, in effect, a spring of short active length.

In any of the various forms of the invention, the governed device responds substantially entirely to rotational speed and is effectively independent of externally applied acceleration and shock forces, regardless of direction. This significantly advantageous arrangement is realized through the use of a pair of symmetrically arranged, separately movable contact elements which are immune to external forces applied in two of the three component directions and are mutually compensating as to forces applied in the third component direction.

The device of the invention, while characterized by the significant operating advantages mentioned above, is at the same time of essentially simplified construction, which renders the device economical to manufacture and relatively foolproof in operation.

@It should be understood, however, that the specific forms of the invention herein illustrated and described are intended to be representative only, and certain changes may be made therein Without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determ ning the full scope of the invention.

We claim:

1. A centrifugal governor mechanism for performing a control function in response to the rotational speed of a shaft and in a manner substantially independent of external forces, comprising a mounting member fixed to the shaft for rotation therewith, a pair of control arm assemblies mounted on said mounting member and arranged with their effective masses symmetrically disposed with respect to a diametrical axis passing through the axis of rotation, each of said control arm assemblies being at one side of the mounting member for like free swinging movement toward and away from each other and having respective portions passing on opposite sides of said shaft, each of said control arm assemblies further having a free end portion movable toward and away from the other, resilient means urging said free end portions into contacting engagement and related to the effective masses of said contact arm assemblies in such manner as to accommd date like separating displacements of both of said free end portions under centrifugal forces resulting from rotation of said shaft and mounting member, each of said contact arm assemblies having an axis passing through the center of swinging movement thereof and the center of gravity thereof and positioned substantially at right angles to the direction of opening and closing movements of the free end portions thereof, the opening and closing movements of said free end portions being substantially colinear.

2. The governor mechanism of claim 1, in which said control arm assemblies form part of an electrical circuit, and electrical contacts are provided at the free end portions of said contact arm assemblies.

3. The governor of claim 2, in which said contact arm assemblies are mounted by stud posts extending from said mounting member and secured rigidly thereto with a glass-to-metal seal.

4. The governor mechanism of claim 1, in which said contact arm assemblies are formed substantially of elements of spring material anchored at one end of said mounting member.

5. The governor mechanism of claim 4, in which each of said spring elements has an end portion formed into a spiral and constituting a spring portion of long effective length, and the end extremities of said spring portion are anchored to said mounting member.

6. The governor mechanism of claim 1, in which said resilient means comprises spring elements connected at ends thereof to free portions of said contact arms and connected at the other ends thereof to said mounting member.

7. The governor mechanism of claim 6, in which a slide member is adjustably received to said mounting member, and the spring elements are connected at their said other ends to said slide member.

8. The mechanism of claim 1, which further includes a second and similar governor mechanism mounted on said mounting member and oriented reversely with respect to the first governor mechanism.

References Cited by the Examiner UNITED STATES PATENTS 1,334,868 3/20 Laycock 318-325 2,165,858 7/39 Jepson 310-68 2,478,848 8/49 Sullivan et al 318-325 2,487,543 11/49 Hansen et a1 318-325 X 2,846,541 8/58 Evans et a1 200- 2,927,173 3/60 Crocco 20080 2,945,101 7/60 Chichester et a1 200-80 2,997,559 8/61 Caton 20080 BERNARD A. GILHEANY, Primary Examiner.

MILTON O. HIRSHFIELD, ROBERT K. SCHAEFER,

Examiners. 

1. A CENTRIFUGAL GOVERNOR MECHANISM FOR PERFORMING A CONTROL FUNCTION IN RESPONSE TO THE ROTATIONAL SPEED OF A SHAFT AND IN A MANNER SUBSTANTIALLY INDEPENDENT OF EXTERNAL FORCES, COMPRISING A MOUNTING MEMBER FIXED TO THE SHAFT FOR ROTATION THEREWITH, A PAIR OF CONTROL ARM ASSEMBLIES MOUNTED ON SAID MOUNTING MEMBER AND ARRANGED WITH THEIR EFFECTIVE MASSES SYMMETRICALLY DISPOSED WITH RESPECT TO A DIAMETRICAL AXIS PASSING THROUGH THE AXIS OF ROTATION, EACH OF SAID CONTROL ARM ASSEMBLIES BEING AT ONE SIDE OF THE MOUNTING MEMBER FOR LIKE FREE SWINGING MOVEMENT TOWARD AND AWAY FROM EACH OTHER AND HAVING RESPECTIVE PORTIONS PASSING ON OPPOSITE SIDES OF SAID SHAFT, EACH OF SAID CONTROL ARM ASSEMBLIES FURTHER HAVING A FREE END PORTION MOVABLE TOWARD AND AWAY FROM THE OTHER, RESILIENT MEANS URGING SAID FREE END PORTIONS INTO CONTACTING ENGAGEMENT AND RELATED TO THE EFFECTIVE MASSES OF SAID CONTACT ARM ASSEMBLIES IN SUCH MANNER AS TO ACCOMMODATE LIKE SEPARATING DISPLACEMENTS OF BOTH OF SAID FREE END PORTIONS UNDER CENTRIFUGAL FORCES RESULTING FROM ROTATION OF SAID SHAFT AND MOUNTING MEMBER, EACH OF SAID CONTACT ARM ASSEMBLIES HAVING AN AXIS PASSING THROUGH THE CENTER OF SWINGING MOVEMENT THEREOF AND THE CENTER OF GRAVITY THEREOF AND POSITIONED SUBSTANTIALLY AT RIGHT ANGLES TO THE DIRECTION OF OPENING AND CLOSING MOVEMENTS OF THE FREE END PORTIONS THEREOF, THE OPENING AND CLOSING MOVEMENTS OF SAID FREE END PORTIONS BEING SUBSTANTIALLY COLINEAR. 